All spectrometers require a radiation source, a wavelength selective or encoding device, and a detector. Analytical spectrometers require a means to transport light to and from a sample, and the sample is commonly examined in transmission or reflection.
An emerging spectrometer design standard employs a semiconductor light source, a scanning filter, and a single element detector; light is carried to and from the sample via fiber optics, and a wide variety of accessories, cells and probes, can be used as the sample interface. Examples of such systems are described in U.S. Pat. Appl. Publ. Nos. US 2006/0072632 A1 and US 2005/0083533, which are incorporated herein by this reference in their entirety. These systems use small, powerful, and efficient semiconductor sources combined with small, stable and efficient microelectromechanical system (MEMS) tunable filters. Theses spectrometers employ MEMS-based tunable Fabry-Perot filters in a pre-dispersive mode; that is with the wavelength selective device before the sample being examined. All the components are affixed to small, such as 14 millimeter (mm) long aluminum nitride, optical benches that sit atop thermoelectric coolers, and all optical coupling on this bench is via free-space micro optics. Collection fiber(s) deliver transmitted or reflected light back to the spectrometer, where a single-element InGaAs detector and transimpedance amplifier convert the light into electrical signals for processing.